/*
 * Copyright (C) 2012 CyberAgent
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.jarlen.photoedit.filter.single;

import android.opengl.GLES20;

import cn.jarlen.photoedit.filter.base.GPUImageFilter;

/**
 * brightness value ranges from -1.0 to 1.0, with 0.0 as the normal level
 */
public class GPUImageBrightnessFilter extends GPUImageFilter
{
	public static final String BRIGHTNESS_FRAGMENT_SHADER = ""
			+ "varying highp vec2 textureCoordinate;\n"
			+ " \n"
			+ " uniform sampler2D inputImageTexture;\n"
			+ " uniform lowp float brightness;\n"
			+ " \n"
			+ " void main()\n"
			+ " {\n"
			+ "     lowp vec4 textureColor = texture2D(inputImageTexture, textureCoordinate);\n"
			+ "     \n"
			+ "     gl_FragColor = vec4((textureColor.rgb + vec3(brightness)), textureColor.w);\n"
			+ " }";

	private int mBrightnessLocation;
	private float mBrightness;

	public GPUImageBrightnessFilter()
	{
		this(0.0f);
	}

	public GPUImageBrightnessFilter(final float brightness)
	{
		super(NO_FILTER_VERTEX_SHADER, BRIGHTNESS_FRAGMENT_SHADER);
		mBrightness = brightness;
	}

	@Override
	public void onInit()
	{
		super.onInit();
		mBrightnessLocation = GLES20.glGetUniformLocation(getProgram(),
				"brightness");
	}

	@Override
	public void onInitialized()
	{
		super.onInitialized();
		setBrightness(mBrightness);
	}

	public void setBrightness(final float brightness)
	{
		mBrightness = brightness;
		setFloat(mBrightnessLocation, mBrightness);
	}
}
